[Gllug] RS232 Programming

[Jackson, Harry]

Hi all

	How hard would it be to write something that would read data from a
serial port to save in a database. In particular data from a Concept II
rowing machine. I am able to get the specifications for it and I would like
something that you can take to the gym on a palmtop so that you could record
your progress etc. The following is a couple of bits that have been written
but I cannot make head nor tail of them. 

PALM OS 3.5 Code - Uses OS 3.5 Libraries - Metrokwerks Codewarrior 
void GetData(char command)
{
	UInt32 baud=9600;		//baud rate
	static  char msgdata[10],	//data to send to PM2+
		readbuffer[32];		// receive data buffer
static UInt16 *refNum;	//port ID of serial port
Err checkst, 		//holds the result of whether  serial port opened
correctly
		error;
	unsigned short rcvdata;	//no. bytes retrieved
	
	msgdata[0]= command;	//send query command-could be 0xb0, 0xb1,
0xb2
	msgdata[1]= 0x00;		//send address of rower, 00 for
single connection

	checkst= SrmOpen (0x8000,baud, refNum); 		//open the
serial port
// (0x8000 is port address of com1)
	if (checkst==0)					//make sure port
opened
	{
		SrmReceiveFlush( *refNum, 1);
//flush any garbage
		SrmSend ( *refNum, &msgdata, 2,&error);
//send command bytes
		if( SrmReceiveWait( *refNum,  5, 50) == 0) 	//wait for 5
byte response
		{
			rcvdata = SrmReceive (*refNum, &readbuffer[0],
5,0,&error); 	//put data into buffer	
		}
		else 
		{	
			HandleTimeout();			//if timeout
occurs prob. want to take palm offline
		}

		SrmClose(*refNum);			// close port after
use
	
		ProcessData(&readbuffer[0]);		//look at data 
	}
	else
	{
		ErrFatalDisplayIf( 1, "Serial Port can't be opened");
//can't open port
	}
	return ;
}
void ProcessData(char *readbuffer)
{
	char status;
	char floatbytearray[4];
	float *floatvalue;
	
	status = readbuffer[0];
	floatbytearray[0] = readbuffer[4];		//convert from Intel
to Motorola byte ordering
	floatbytearray[1] = readbuffer[3];		//because PALM uses
a Motorola based processor
	floatbytearray[2] = readbuffer[2];		//windows machines
don't have to reverse the bytes
	floatbytearray[3] = readbuffer[1];
			
	floatvalue = (float*) floatbytearray;		//convert 4 byte
array into a floating point number
	CheckStatus(status);
	Display(*floatvalue);
}
 
An example using the win32api calls. This routine compiled and run under
Borland C++Builder 4.0. 
void getdistance(void)
{
	HANDLE hComm = NULL;
	COMMTIMEOUTS ctmoNew = {0}, ctmoOld;
	char tempfloatarray[4];
	char InBuff[100];
	unsigned long int dwBytesRead;
	char status;
	float *ergdistance;

	DCB dcbCommPort;
// OPEN THE COMM PORT.
	hComm = CreateFile("COM1", GENERIC_READ | GENERIC_WRITE, 0, 0, 
	
OPEN_EXISTING, 0, 0);
	if(hComm == INVALID_HANDLE_VALUE)
                AppQuit();      				//quit on
port failure-insert your own routine
  									//
SET THE COMM TIMEOUTS.
	GetCommTimeouts(hComm,&ctmoOld);
	ctmoNew.ReadTotalTimeoutConstant = 100;
	ctmoNew.ReadTotalTimeoutMultiplier = 0;
	ctmoNew.WriteTotalTimeoutMultiplier = 0;
	ctmoNew.WriteTotalTimeoutConstant = 0;
	SetCommTimeouts(hComm, &ctmoNew);

  // SET BAUD RATE, PARITY, WORD SIZE, AND STOP BITS.
  // THERE ARE OTHER WAYS OF DOING SETTING THESE BUT THIS IS THE EASIEST.
  // IF YOU WANT TO LATER ADD CODE FOR OTHER BAUD RATES, REMEMBER
  // THAT THE ARGUMENT FOR BuildCommDCB MUST BE A POINTER TO A STRING.
  // ALSO NOTE THAT BuildCommDCB() DEFAULTS TO NO HANDSHAKING.

	dcbCommPort.DCBlength = sizeof(DCB);
	GetCommState(hComm, &dcbCommPort);
	BuildCommDCB("9600,N,8,1", &dcbCommPort);
	SetCommState(hComm, &dcbCommPort);

	TransmitCommChar(hComm, 0xb0);       //transmit distance query
	TransmitCommChar(hComm, 0x00);        	// erg address -always zero

	ReadFile(hComm, InBuff, 5, &dwBytesRead, NULL);   
	
//read the serial port
	if(dwBytesRead)
	{
		status = InBuff[0];
		tempfloatarray[0] = InBuff[1];
		tempfloatarray[1] = InBuff[2];
		tempfloatarray[2] = InBuff[3];
		tempfloatarray[3] = InBuff[4];
		ergdistance = (float*)&tempfloatarray;
	}
	if(hComm)
	{
		SetCommTimeouts(hComm, &ctmoOld);     //restore old settings
		CloseHandle(hComm);
	}
}


Regards;
Harry Jackson.


     



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